A vehicular power transmitting apparatus including an electrically controlled differential portion is known. In the electrically controlled differential portion, a differential state of rotation speeds between an input shaft to which an internal combustion engine is connected and an output shaft is controlled, by controlling an operational state of an electric motor connected to a rotary element of a differential mechanism in a power transmissive state. For example, a power output device disclosed in Patent Literature 1 (Japanese Patent Publication No. H10-306739) may be one example of such a power transmitting apparatus. In the vehicular power transmitting apparatus thus structured, the differential mechanism is comprised of, for example, a planetary gear unit having rotary elements of which rotations are controlled by controlling the electric motor connected to the rotary element in the power transmissive state.
It is well known that a torsional vibration or twisting vibration is generated in a power transmitting system by torque variations in an internal combustion engine resulting from a rotational motion thereof. The torsional vibration is amplified by a resonance phenomena of the power transmitting system, and is then transmitted to a vehicle body. Generally, a resonance area (resonance point) falls within a low rotation speed area of the internal combustion engine in which the rotation speed is less than an idle rotation speed. In a stopping process of the internal combustion engine in a differential manner, when the rotation speed falls within the resonance point, there is a fear of the above-mentioned resonance phenomena being caused. In view of this, in Patent Literature 1, upon stopping the internal combustion engine, the rotation speed thereof is controlled by controlling the electric motor to quickly pass through the resonance point, for thereby preventing occurrence of the resonance phenomena.
However, for example, if a charge/discharge of a battery supplying electric power to the motor is limited, the operational state of the electric motor is limited. If the internal combustion engine is controllably stopped by the electric motor in this state, limitation is imposed on an output torque output from the electric motor, which may lengthen a time period necessary for decreasing the rotation speed of the internal combustion engine. Thus, in a decreasing process of the rotation speed of the internal combustion engine, there is a fear that longer time period is required to pass through the resonance point, causing resonance phenomena.